Air Conditioner Cycle Times Post-Hunter 44860 Installation

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Old 06-25-09, 10:19 PM
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Air Conditioner Cycle Times Post-Hunter 44860 Installation

Hi All,

I live in the AZ desert and just installed a Hunter 44860 t-stat, replacing a mercury-based t-stat that I presume was installed by the original home builder in 1989 (I recently purchased this house). After some initial difficulties in getting the wiring set-up correctly (4-wire system, no labeling, conflicting instructions), I finally got it figured out (or so I think). But now, I'm finding a SIGNIFICANT difference in cycle times and am seeking feedback.

Specifically, it took my house 70 minutes to cool from 83 to 80 degrees this mid-morning. I didn't put too much weight in that because some humidity had built up, and I have a 2-story home in AZ, and it was already in the 90's in the AM...and then when the A/C didn't activate again for 75 mins, I thought, OK, but that sure is a long time compared to any other unit I've dealt with. I then started charting the cycles and here were the results:

A/C On? Duration Degree Differential
Yes 70 min -3
No 75 min +2
Yes 34 min -2
No 43 min +2
Yes 42 min -2
No 39 min +2
Yes 42 min -2
No 42 min +2
Yes 48 min -2
No 23 min +2
Yes 38 min -2

At this time, I had had enough, it was nearing the hottest time of the day, and I decided to re-install the merc t-stat for a comparison.

Well, the cycles with the merc t-stat installed have been incredibly consistent at only 8 or 9 mins, both on or off, for -2 or +2 degree differentials. The only difference being, obviously, that these readings are being obtained as dusk hit and nighttime came, all-be-it it's still in the 90's as I gype this (9:15PM).

I would really like to know which is normal, or preferred, if either. I've read so many different things and don't know what to believe. The digital t-stat is much more accurate as far as the temp reading is concerned (also have another device hooked up next to the t-stat for comparisons), and I'd also think that it's better for the A/C to run for longer intervals instead of shorter spurts, but 30-45mins at a time for just a couple of degrees seems pretty extreme. Then again, it's taking that long for the A/C to kick back on, and it is AZ in late June.

Any feedback you can provide would be much appreciated!
 
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Old 06-27-09, 07:50 AM
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I have a Honeywell t-stat, and they don't go by swing.

A long run time is going to be more effecent, but the large temp swing is no comfort.

The stop and go is harder on the compressor.

When we hit 90's+ my system runs non stop (working at design temps)

As for Hunter t-stat, there is a alot of mixed results with them.
 
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Old 08-28-09, 06:06 AM
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AC cycle-time question

i have a hunter thermostat also and am wondering what the "normal" cycle time should be. I really can’t supply information on the size of my condo or the AC “strength.” My AC originally came on for over a hour and was worried the cycle-time was too long. My AC seems to output cool air but the thermostat is slow to show that. I changed settings “SPAN” on my thermostat to increase/decrease the cycle-times also, whether I point the output vents more at my thermostat to cool the thermostat down faster and decrease the cycle-time. By doing both these, I’ve gotten it (cycle-time) down to less than 10 minutes (AC is on then about 10 minutes off the same, repeatedly) which I think is too fast. I am wondering what I should shoot for? I’ve “googled” it, but have only found that the longer the cycle-time, the more efficient the AC works but I feel like it is wasting electricity when it runs for so long.
 
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Old 08-28-09, 07:37 AM
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Originally Posted by tdp1018 View Post
i have a hunter thermostat also and am wondering what the "normal" cycle time should be. I really can’t supply information on the size of my condo or the AC “strength.”
Guess I will not be able to say if the system is oversized or not with out any info.


I point the output vents more at my thermostat to cool the thermostat down faster and decrease the cycle-time. By doing both these, I’ve gotten it (cycle-time) down to less than 10 minutes (AC is on then about 10 minutes off the same, repeatedly) which I think is too fast.
Move the air flow away from the t-stat. You are getting a false reading by doing this, and making the system cycle on and off too often.

have only found that the longer the cycle-time, the more efficient the AC works but I feel like it is wasting electricity when it runs for so long.
The stop and go is harder on your equipment, and takes more energy to get up to speed.

A perfect example, with your car. You get better gas mileage when you stop and go in town, or with the cruise on the highway?

Have you checked the coil on the unit outside to make sure it's clean and has good air flow, and staying on top of the air filter?
 
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Old 08-28-09, 07:58 AM
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thanks Jay11J,

I'm guessing the size is fine because it was just installed when i bought the place and really had no noticeable problems until this year when the AC stayed on for over a hour, and that poked my curiosity.

i have moved the vents away from pointing at the t-stat; I just did that because the cycle time seemed too long.

I've been very good about changing the filter (and having professional maintenance done every year EXCEPT this year because of the economy) and have never personally cleaned the coil outside (thats in the fan unit outside, right?) If you don't mind, can you give me some basic instructions on how to do that?

Thanks
 
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Old 08-28-09, 04:05 PM
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Originally Posted by tdp1018 View Post
thanks Jay11J,
I'm guessing the size is fine because it was just installed when i bought the place and really had no noticeable problems until this year when the AC stayed on for over a hour, and that poked my curiosity.
I don't know where you are out of, but if you're in the area where it has been hotter than normal, then it will run longer. Ideal design of an A/C system is when it's temps outside is at hottest day the system should run non-stop and be able to keep up.

I've been very good about changing the filter (and having professional maintenance done every year EXCEPT this year because of the economy) and have never personally cleaned the coil outside (thats in the fan unit outside, right?)
Yes, it's the unit outside. If you do the mainteance again, look at the contract to see what they should be doing.. My company we pretty much took the whole unit apart outside to clean it, and check every thing over.

If you don't mind, can you give me some basic instructions on how to do that?
What is the make and model of the unit outside? (There will be a sticker with the info on it)
 
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Old 08-28-09, 04:37 PM
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I didn't realize it should run that much...yes, its seems to play catch-up a lot. I'm in Fort Lauderdale, Florida so it sounds like it is working properly.

Like I said before, I normally have the unit serviced twice a year (on a maintenance plan) but did not this year to save a few bucks.

Its a Rheem RAPA-030JAZ and the condo is a little over 1,000 square feet.

Thanks again
 
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Old 08-28-09, 04:59 PM
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Originally Posted by tdp1018 View Post
I didn't realize it should run that much...yes, its seems to play catch-up a lot. I'm in Fort Lauderdale, Florida so it sounds like it is working properly.
Yeah the run time gives you a much better comfort, it will be able to remove the humidity from the air. Otherwise, if it was oversized or cycles on and off often the humidity won't have a chance to get out of the air.


Its a Rheem RAPA-030JAZ and the condo is a little over 1,000 square feet.
I am not able to pull this model # up. It may be an older model. Is your unit low/flat type unit?
 
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Old 08-28-09, 05:36 PM
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I have no idea what a low/flat type unit is? I'm on the second floor and part of the unit is in my attic and the other is on the ground about 3X4X2 with a fan inside (all enclosed.)
 
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Old 08-28-09, 07:00 PM
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A unit like this?

 
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Old 08-28-09, 07:06 PM
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I'm not sure what else there is but that looks like it.
 
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Old 08-28-09, 07:35 PM
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Ok, TURN OFF POWER for the unit outside.

Then take a 5/16 nut driver and undo the nuts on the back of the unit, that should lift up, an you'll see the compressor and wire box.

Discharge the capacitors.

Then undo the fan top and remove the fan top and carefully set aside with the wires in place. If you must undo the wire again be sure you discharge the capacitors, and make notes of what wire went where.

Then remove the outer shell of the unit to get a good view of the coil.

Pick out any leaves and what not that is inside of the unit. then take a garden hose and spray from the inside out to flush out any lint dirt and what not that is build up on the coil.

You may use Simple Green to help clean the coil better.

Be sure not to get water into the wire/control area.

Then put everything back together.
 
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Old 08-28-09, 07:48 PM
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I'm an engineer but not sure how to "Discharge the capacitors" in an AC unit. "Simple Green" is a cleaner I can buy at home depot, right? Everything else I understand.

Thanks and I'm sure I'll have more questions...
 
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Old 08-28-09, 08:08 PM
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Take an insulated handle screwdriver, and put the screw driver between the two terminal of the capacitor and that will ground it out. If there 3 then do middle to end, and then again on the other end to middle. Wait for about a minute or two and do it again.

If you don't discharge it, you'll be zapped pretty good.

Yes, Simple Green is sold at Home Depot.
 
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Old 09-15-09, 05:14 AM
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Cycle Time & Hard Start

I have a Carrier Silencer 2000. My house is about 2,500 Sq. Ft.
A few weeks ago I noticed the house wasn't cooling but the inside unit was running. I found the outside unit was "humming". After some diagnosis I found the capacitor was bad. I replaced it, everything ran great.

Over the past few weeks I've noticed the unit has a short cycle, about 8-10 minutes on and off. This isn't what I remember as being normal. The air differential is about 20 deg F. The unit is set on 76, I'm getting 56-58 deg. out the vents. It's blowing cold. However, the unit will run for about 7 minutes, then the outside unit shuts off. The inside unit runs for about the last 2 minutes, the air warms and it shuts off. Seems normal for this system?

I realize this is a common question but can the quick cycle be the sign of a problem? Since I had the capacitor problem the outside unit has had a "Hard Start" twice. Meaning the inside unit is running but the outside is not running, just humming. If I turn off the inside unit for a minute then turn back on, the unit outside will come on.

Is it possible I have a pressure equalization problem due to the short cycle times?
Is it possible there is a low voltage problem? If so, would this have any effect on the cycle time? If so, where should I check for low voltage, at the capacitor or the wires going to the compressor?

Lots of questions, answers are greatly appreciated.
 
 

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